Introduce memory controller mini-framework

From: Thierry Reding <treding@nvidia.com>

Hi,

this series proposes the introduction of a mini-framework for memory
controllers. The primary use-case for this right now is to allow for
drivers that depend on the memory controller to defer probe until the
memory controller has been successfully registered.

One example where this is needed is on Tegra186 and later SoCs where
the memory controller needs to program some registers to associate a
stream ID with memory clients. This requires that the IOMMU driver
defers probe until the memory controller has been registered.

This is achieved by providing a trivial memory controller registry that
can be queried.

I haven't written up a full device tree binding for this, but if people
think this is a reasonable proposal, I can flesh things out. Currently I
use something along these lines on Tegra186:

	mc: memory-controller@2c00000 {
		...
		#memory-controller-cells = <0>;
		...
	};

	iommu@12000000 {
		...
		memory-controllers = <&mc>;
		...
	};

Thierry

Thierry Reding (3):
  memory: Introduce memory controller mini-framework
  memory: tegra186: Register as memory controller
  iommu: arm-smmu: Get reference to memory controller

 drivers/iommu/arm-smmu.c          | 12 ++++
 drivers/iommu/arm-smmu.h          |  2 +
 drivers/memory/Makefile           |  1 +
 drivers/memory/core.c             | 99 +++++++++++++++++++++++++++++++
 drivers/memory/tegra/tegra186.c   |  8 ++-
 include/linux/memory-controller.h | 25 ++++++++
 6 files changed, 146 insertions(+), 1 deletion(-)
 create mode 100644 drivers/memory/core.c
 create mode 100644 include/linux/memory-controller.h

-- 
2.23.0


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